1. Field of the Invention
This invention relates generally to a clutch and particularly to a clutch with no relative rotational movement between the sheaves.
2. Description of the Prior Art
In a driven clutch, there are two sheaves. The first is called a stationary sheave because it is locked rigidly to the post. The other sheave is called moveable because it translates along the cam profile of a cam. The cam profile is for torque sensing. As the moveable sheave moves along the cam, the moveable sheave rotates about the post and slides linearly closer to or further away from the stationary sheave due to the cam angle. This continuously variable transmission delivers torque by squeezing a belt tight enough to prevent slipping. The cam angle allows the continuously variable transmission to be torque sensing. The more torque that is put into the continuously variable transmission, the tighter the continuously variable transmission squeezes the belt. This will shift the continuously variable transmission into a lower ratio. Likewise, when the torque drops, the continuously variable transmission exerts less belt squeeze because of the reaction force in the cam allows the continuously variable transmission to shift into a higher ratio. This feature gives continuously variable transmissions of this type their torque sensing capabilities. In the prior art, the continuously variable transmissions with the two sheaves separate, the torque going through the cam is half the torque through the secondary clutch. The other half goes directly through the stationary sheave into the post that is fixed to it. To change ratios, the movable sheave, which typically has a 13 to 16 degree angle on the sheave face, rotates about the post on the cam, moving away from the stationary sheave, changing the pitch diameter of the belt, thereby changing the ratio of the continuously variable transmission. In the prior art, the moveable sheave follows the cam profile, which causes relative rotational motion between the moveable and stationary sheaves. This in turn causes undesirable friction between the faces of the belt and the stationary and moveable sheaves. This friction loss is called belt smear. This smearing is detrimental to belt life and is a performance and efficiency loss. Current systems squeeze the belt with between 300 to 1,000 pounds. When this much force is present, energy is wasted in smearing the belt.
The present invention addresses the problems associated with the prior art continuously variable transmissions and provides for a driven clutch with no relative rotation between the two sheaves.
The present invention is a torque-sensing clutch including a post. A first sheave is operatively connected to the post. The first sheave is rotatable on the post and is stationary relative to longitudinal movement on the post. A second sheave is longitudinally moveable and rotatable on the post. A first connector operatively connects the post to the second sheave for rotating the second sheave and for moving the second sheave longitudinally on the post. A second connector operatively connects the first and second sheaves, wherein the first and second sheaves rotate together and reduce belt smear.
In a second embodiment, the present invention is a continuous variable transmission driven element for mounting on a rotatable shaft. The driven element is adapted for use in a belt-type continuous variable transmission operatively connected by an endless belt to a drive element. The driven element includes a post adapted and configured to be operatively connected to a rotatable shaft. A housing is operatively connected to the post, the housing rotatable on the post and being stationary relative to longitudinal movement on the post. A first conical-faced belt contacting coaxially mounted sheave portion is operatively connected to the housing. A second conical-faced belt contacting coaxially mounted sheave portion is longitudinally moveable on the post and is rotatable on the post. A connector is operatively connecting the first and second sheave portions, wherein rotation of the second sheave portion causes rotation of the first sheave portion and reduces belt smear. A cam, having a cam surface, is operatively connected to the second sheave portion. A spider is operatively connected to the post, the spider having a sliding member which is positioned on the cam surface, wherein rotation of the cam on the spider moves the second sheave portion longitudinally and rotationally on the post. A compression spring is positioned between the spider and second sheave portion.
In a third embodiment, the invention is a continuous variable transmission driven element for mounting on a rotatable shaft. The driven element is adapted for use in a belt-type continuous variable transmission operatively connected by an endless belt to a drive element. The driven element includes a post adapted and configured to be operatively connected to a rotatable shaft. A housing is operatively connected to the post, the housing rotatable on the post and being stationary relative to longitudinal movement on the post. A first conical-faced belt contacting coaxially mounted sheave portion is operatively connected to the housing. A second conical-faced belt contacting coaxially mounted sheave portion is longitudinally moveable on the post and is rotatable on the post. A means for connecting the first and second sheave portions is provided, wherein rotation around the post by both sheave portions is equivalent, thereby reducing the belt smear. The connecting means provide for longitudinal movement of the second sheave portion on the post. A cam, having a cam surface, is operatively connected to the second sheave portion. A spider is operatively connected to the post, the spider having a sliding member which is positioned on the cam surface, wherein rotation of the cam on the spider moves the second sheave portion longitudinally and rotationally on the post. A compression spring is positioned between the spider and second sheave portion.